One shot heat exchanger burner

ABSTRACT

A single burner, heat exchanger combination for particular use in a hot air furnace, includes a plurality of spaced heat exchangers, each heat exchanger having an inlet port for receipt therein of combustion gases. A unitary burner for producing combustion gases includes a burner face defined by a plurality of spaced fins for passing therethrough a combustible gas. The inlet ports of each of the heat exchangers are disposed adjacent to and in fluid communication with the passages defined by the burner face fins. A hot air furnace comprising the single bumer, heat exchanger combination also includes a blower adapted to blow air over the heat exchangers and an induction blower in fluid communication with the outlets of the heat exchanger adapted to draw the combustion gases through the heat exchangers and to discharge such combustion gases outwardly from the furnace. An igniter is disposed on a support frame around the burner face for igniting the combustible gas flowing through the burner face fins for flow of combustion gases through the heat exchangers.

CROSS-REFERENCE TO RELATED APPLICATION:

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/336,956 filed on Dec. 5, 2001.

FIELD OF THE INVENTION

The present invention relates generally to an improved heat exchangerburner and, more particularly, to a single burner used in combinationwith a plurality of heat exchangers.

BACKGROUND OF THE INVENTION

Gas fired hot air furnaces have long been used to heat spaces in bothresidential and commercial settings. Most conventional gas firedfurnaces include a plurality of heat exchangers, spaced apart to allowair flow therebetween. The heat exchangers define an internal flow pathfor hot combustion gases supplied by burners. Heat transferred throughthe heat exchangers may be used to effect heating of a particular area.

A common arrangement for gas fired furnaces is to provide an individualburner associated with each heat exchanger. This arrangement is shownschematically in FIG. 1. A fuel gas mixture 10 is delivered through amanifold 12. The manifold has a plurality of outlets 14 correspondingwith the number of heat exchangers 16 employed in the furnace.Interposed between the heat exchangers and the manifold outlets are aplurality of burners 18 provided in one-to-one correspondence to thenumber of heat exchangers. The burners may be of conventionalconstruction of the type shown in U.S. Pat. No. 6,196,835 which isincorporated by reference herein for all purposes. Each burner includesa venturi device which provides for the proper mixture of air and fuel.The air and fuel is combined at one end of the burner 18 adjacent themanifold 12 and the air/fuel mixture is ignited adjacent the oppositeend of the burner 18 at a burner face 18a. The hot combustion gasesenter each heat exchanger and are caused to flow in a tortuous pathwithin each heat exchanger.

The individual burner/heat exchanger arrangement is more particularlyshown in U.S. Pat. No. 4,467,780 and is generally described herein withreference to FIG. 2. As shown in FIG. 2, the typical hot air furnace 20has a sheet metal outer covering 22 which encases a series of five heatexchangers 24, blower 26, burners 28, one burner for each heat exchanger24, and a pressure regulator 30. The gas/air mixture is injected byburner 18 into the open end of a heat exchanger 24. As a part of theinjection process, additional air is drawn into the heat exchanger 24 sothat the gas may be fully combusted within the heat exchanger 24. Aheader 32 is connected to the exhaust portion of each of the heatexchangers 24, header 22 also being connected to an induction draft fan34 which creates a negative pressure through the heat exchangers 24 anda positive exhaust pressure to discharge the gases resulting fromcombustion through opening 36 to the discharge flue. Blower 26 receivescold room air from the area which is to be heated, forces that air overthe heat exchanger surfaces in the direction indicated by arrow 38, theair then being collected and returned to the rooms to be heated.

It should be appreciated that the arrangement shown in FIG. 2 requiresmultiple burners to be provided so that each heat exchanger employs anassociated burner. Use of multiple burners generally increases the costof the furnace unit. Furthermore, as multiple burners must beindividually ignited, a manifold must be used to bring the gas fuel tothe burner. The manifold must employ specifically configured orifices atthe openings 14 to provide the proper amount of gas to each burner. Themanufacture and maintenance of this manifold device also increases thecost of manufacture and maintenance of the furnace. Furthermore, incertain situations there is a desire to switch between two types of fuelsources such as natural gas and propane. The manifold devices arespecifically manufactured to handle one type of fuel source.Accordingly, a conversion from one fuel source to another may requirethe alteration or replacement of the burners. Furthermore, the efficientoperation of the furnace depends largely on the proper burning of eachburner. In a multiple burner situation, it is often difficult to detectimproper operation of an individual burner. Improper operation of anyindividual burner may result in the creation of undesirable combustionproducts and/or reduce the operating life of the heat exchanger.

SUMMARY OF THE INVENTION

In accordance with the present invention, the foregoing disadvantages ofthe prior art are addressed. In accordance with one aspect of theinvention, a single burner, heat exchanger combination for a fuel-firedfurnace comprises a plurality of spaced heat exchangers, each heatexchanger having an inlet port for receipt therein of combustion gases.A unitary burner is provided for producing combustion gases, the burnerhaving a burner face for passing therethrough a combustible gas. Theinlet ports of each heat exchanger is disposed adjacent to and in fluidcommunication with the burner face, whereby combustion gases may flowfrom the burner into each of the inlet ports of the heat exchangers.

In accordance with a particular arrangement of the present invention, ahot air furnace comprises a furnace outer covering and a plurality ofheat exchangers supported within the covering in spaced arrangement,each heat exchanger having an inlet port and an outlet. A unitary burneris provided for producing combustion gases, the burner having a burnerface for passing therethrough a combustible gas, the burner beingsupported within the covering with the burner face being disposedadjacent to and in fluid communication with all of the heat exchangerinlet ports, whereby combustion gases may flow from the burner into eachof the inlet ports of the heat exchangers. A blower adapted to blow airover the heat exchangers is provided. An induction blower is alsoprovided in fluid communication with the outlets of the heat exchangers,the induction blower being adapted to draw the combustion gases throughthe heat exchangers and to discharge such combustion gases outwardlyfrom the furnace outer covering.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a prior art burner system foruse with a plurality of heat exchangers in a hot air furnace, with oneburner being associated correspondingly with each heat exchanger.

FIG. 2 is a perspective view of a prior art hot air furnace, partlybroken away to reveal internal details, the furnace incorporating amultiple burner unit as schematically illustrated in FIG. 1.

FIG. 3 is a side elevation view of a single burner in accordance withthe present invention for use with a plurality of heat exchangers in ahot air furnace.

FIG. 4 is a top plan view of the single burner, plural heat exchangersystem of FIG. 3.

FIG. 5 is a cross-sectional view of the single burner plural heatexchanger arrangement of FIG. 4 as seen along viewing lines V-V.

FIG. 6 is a top perspective view of the single burner of FIG. 3.

FIG. 7 is an exploded view of the single burner of FIG. 6.

FIG. 8 is a perspective view of a ribbon tray defining a burner face ofthe single burner of FIG. 6.

FIG. 9 is an exploded view of the burner tray of FIG. 8 showing detailsof the burner ribbons of the burner face.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning now to the drawings, there is shown in FIGS. 3, 4 and 5 a singleburner 40 for use with a plurality of heat exchangers 42. The singleburner 40 in combination with the multiple heat exchangers 42 may beused in a hot air furnace such as that described in U.S. Pat. No.4,467,780 described herein with respect to FIG. 2, the function andoperation of which is herein incorporated by reference. In a preferredarrangement, heat exchangers 42 are of the type more particularlydescribed and illustrated in commonly-owned, copending patentapplication, U.S. Ser. No. ______ , entitled “COMPACT HIGH EFFICIENCYCLAM SHELL HEAT EXCHANGER”, filed on even date herewith, the disclosureof which is incorporated herein by reference in its entirety.

Referring now also to FIGS. 6 and 7, further details of the singleburner 40 are described. Bumer 40 includes a housing 44 having an upperwall 44 a, a lower wall 44 b, a rear wall 44 c, and two opposingsidewalls 44 d and 44 e. Bumer face 46, the details of which will bedescribed hereinbelow, defines the front wall of burner housing 44.Upper and lower walls 44 a and 44 b, rear wall 44 c and burner face 46,and sidewalls 44 d and 44 e define a hollow mixing chamber 48 forair/gas mixture as will be described.

In the arrangement being described with respect to FIGS. 6 and 7, upperwall 44 a, rear wall 44 c and bottom wall 44 b are formed from a singlesheet of suitable material, such as cold-rolled steel, and are suitablyfolded as shown using conventional metalworking techniques. Sidewalls 44d and 44 e are also formed of suitable material, such as cold-rolledsteel, and are joined to the upper wall 44 a, lower wall 44 b, and rearwall 44 c by suitable fasteners.

Attached to upper wall 44 a of burner housing 44 and projectingoutwardly therefrom is a venturi tube 50. The venturi tube 50 is, in oneparticular arrangement, of generally cylindrical configuration having aninterior opening 50 a communicating with mixing chamber 48 of burnerhousing 44. Attached to the free distal end of venturi tube 50 is abracket 52 defining a gas orifice 52 a. Suitably attached to bracket 52(but not shown) is a gas valve for supplying gas into the venturi tubeopening 50 a. Air is also drawn into the venturi tube opening 50 a forflowing into housing chamber 48 and mixing with the supplied gas, asdepicted in FIG. 3. While the supplied gas in the arrangement beingdescribed is natural gas, it should be understood that other fuels, suchas propane gas, may be used with the burner of the subject invention.

Turning now also to FIGS. 8 and 9, the details of the burner face 46 aredescribed. The burner face 46 includes a ribbon tray 54 having aplurality of spaced fins 56 supported by a pair of opposing sidebrackets 58 and 60 and end brackets 62 and 64. Fins 56 are formedpreferably in ribbon fashion, whereby a continuous strip of suitablemetal, such as steel, is folded back and forth upon itself to define theseries of spaced fins 56. Maintenance of desired spacing betweensuccessive fins 56 is provided by one or more bosses 66 formed on theplanar surfaces of the fins 56, the bosses being formed to project at aselected height to form the desired spacing between successive fins 56.While spaced fins 56 are preferably formed, as described, in ribbonfashion, it should be understood that a plurality of individual fins mayalso be used in the burner face 46.

In the particular arrangement of the ribbon tray 54 as shown in detailin FIG. 9, the plurality of spaced fins 56 are preferably arranged inthree ribboned sections 68, 70 and 72. Intermediate lateral brackets 74and 76 are provided to separate the ribboned sections. The ribbonedsections 68, 70 and 72, together with end brackets 62 and 64 andintermediate brackets 74 and 76, are supported within channels 58 a and60 a on respective side brackets 58 and 60.

Referring again to FIGS. 3, 4 and 5, the operation of the single burnerin a gas-fired furnace is described. A support frame 78 is suitablysecured to the burner housing 44 adjacent the burner face 46. Thesupport frame is suitably secured to the furnace (not shown) such thatthe burner face 46 faces and is located adjacent to the clamshell heatexchangers 42. The support frame 78 also functions as a secondary airshield around the single burner 40. Supported by support bracket 78 at alocation between burner face 46 and the inlet ports 42 a of each of theheat exchangers 42 is an igniter 80. Igniter 80 is suitably wired toprovide an electrical spark for igniting the air/gas mixture flowingthrough the fins 56 of burner face 46, as will be described.

In operation, gas, such as natural gas, is supplied into the venturitube 50 where a quantity of air is also introduced. The supplied gas andintroduced air are drawn into the burner mixing chamber 48 as a resultof the suction pressure produced by an induction draft fan 36 which isconnected to the exhaust ports of the heat exchangers 42. The air/gasmixture drawn through the burner face 46 is ignited by igniter 80causing combustion of the air/gas mixture. As a result of the negativepressure in each heat exchanger 42, a flame 82 forms in each heatexchanger through inlet port 42 a. The relatively narrow passagesbetween the spaced fins 56 of the ribbon tray 54 at the burner face 46cause an increase in the velocity of the air/gas mixture as well asenhanced stability of the air/gas mixture flowing therethrough. The flowpassages between the spaced fins 56 also contribute to resistance toflame flashback. In particular, the mass, spacing and depth of thespaced fins 56 act together to lower the flame velocity to match thevelocity of the unburned air-gas mixture passing through the spaced fins56. An air-gas mixture that is too high will cause the flame to “lift”and burn in front of the spaced fins 56. An air-gas mixture that is toolow will result in the flame “flashing” through the spaced fins 56. Aproper air-gas velocity allows the flame to burn at the outside frontedge of the spaced fins 56 in the burner 40. The spacing between fins56, which is also a factor in controlling the resistance of the burnerto flame flashback, may be adjusted by varying the height of the bosses66 between fins. Furthermore, the spaced fins 56, particularly in theribboned arrangement, are free to expand and contract during the heatingand cooling cycles so as to reduce the mechanical stress occurringduring operation of the burner, and to thereby provide longer operatinglife.

It should now be appreciated that the single burner arrangement, asdescribed herein, provides significant advantages over the conventionalmultiple burner configurations. For example, cost savings may berealized as a result of the elimination of the gas manifold used in themultiple burner arrangement as well as a reduction in the number ofindependent burners. In addition, the single burner replaces multipleorifices with a single orifice that more effectively meters the properamount of combustible air/gas mixture flowing through the burner face.

Having described the preferred embodiments herein, it should now beappreciated that variations may be made thereto without departing fromthe contemplated scope of the invention. Accordingly, the preferredembodiments described herein are deemed illustrative rather thanlimiting, the true scope of the invention being set forth in the claimsappended hereto.

1. A single burner, heat exchanger combination for a fuel-fired furnace,comprising: a plurality of spaced heat exchangers, each heat exchangerhaving an inlet port for receipt therein of combustion gases; and aunitary burner for producing combustion gases, said burner having aburner face for passing therethrough a combustible gas, said inlet portsof each heat exchanger being disposed adjacent to and in fluidcommunication with said burner face, said burner face including meansfor controlling the flow of the combustion gases at the burner face,whereby combustion gases may flow from the burner into each of the inletports of said heat exchangers.
 2. The combination of claim 1, whereinsaid burner has a mixing chamber for receipt therein of combustible gas,said mixing chamber communicating with said burner face.
 3. Thecombination of claim 2, wherein said burner comprises spaced wallsdefining said mixing chamber.
 4. The combination of claim 3, whereinsaid burner comprises a venturi tube supported by one of said walls,said venturi tube having an interior opening communicating with saidmixing chamber.
 5. The combination of claim 2, wherein said controllingmeans at said burner face comprises a plurality of individual flowpassages for passing said combustible gas therethrough.
 6. Thecombination of claim 5, wherein said flow passages are defined by aplurality of spaced fins.
 7. The combination of claim 6, wherein saidfins are spaced by one or more bosses disposed on selected fins, theheight of said bosses being selected to provide desired fin spacing. 8.The combination of claim 6, wherein said fins are defined by a singlecontinuous strip of material formed in ribbon fashion.
 9. Thecombination of claim 8, wherein said fins are arranged in separatesections of ribboned fins.
 10. A hot air furnace, comprising: a furnaceouter covering, a plurality of heat exchangers supported within saidcovering in spaced arrangement, each heat exchanger having an inlet portand an outlet port; a unitary burner for producing combustion gases,said burner having a burner face for passing therethrough a combustiblegas, said burner being supported within said covering with said burnerface being disposed adjacent to and in fluid communication with all ofsaid heat exchanger inlet ports, means for controlling the flow of thecombustion gases at said burner face, whereby combustion gases may flowfrom the burner into each of the inlet ports of said heat exchangers; ablower adapted to blow air over the heat exchangers; and an inductionblower in fluid communication with the outlets of said heat exchangersadapted to draw the combustion gases through the heat exchangers anddischarge such combustion gases outwardly from the furnace outercovering.
 11. A hot air furnace according to claim 10, wherein saidburner comprises spaced walls defining a mixing chamber, said mixingchamber communicating with said burner face.
 12. A hot air furnaceaccording to claim 11, wherein said burner comprises a venturi tubesupported by one of said burner walls, said venturi tube having aninterior opening communicating with said mixing chamber.
 13. A hot airfurnace according to claim 11, further including a support framesupported by walls of said burner adjacent to and substantially aroundthe burner face.
 14. A hot air furnace according to claim 13, furtherincluding an igniter supported by said support frame between said burnerface and the inlet ports of said heat exchangers.
 15. A hot air furnaceaccording to claim 14, wherein said controlling means at burner facecomprises a plurality of individual flow passages for passing saidcombustible gas therethrough.
 16. A hot air furnace according to claim15, wherein said flow passages are defined by a plurality of spacedfins.
 17. A hot air furnace according to claim 16, wherein said fins arespaced by one or more bosses disposed on selected fins, the height ofsaid bosses being selected to provide desired fin spacing.
 18. A hot airfurnace according to claim 17, wherein said fins are defined by a singlecontinuous strip of material formed in ribbon fashion.
 19. A hot airfurnace according to claim 18, wherein said fins are arranged inseparate sections of ribboned fins.
 20. A hot air furnace according toclaim 19, wherein said sections of ribboned fins are supported by saidburner walls by brackets.